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/*
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 * G.729 decoder
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 * Copyright (c) 2008 Vladimir Voroshilov
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include <stdlib.h>
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#include <inttypes.h>
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#include <limits.h>
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#include <stdio.h>
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#include <string.h>
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#include <math.h>
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#include <assert.h>
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#include "avcodec.h"
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#include "libavutil/avutil.h"
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#include "get_bits.h"
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#include "g729.h"
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#include "lsp.h"
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#include "celp_math.h"
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#include "acelp_filters.h"
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#include "acelp_pitch_delay.h"
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#include "acelp_vectors.h"
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#include "g729data.h"
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/**
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 * minimum quantized LSF value (3.2.4)
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 * 0.005 in Q13
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 */
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#define LSFQ_MIN                   40
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/**
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 * maximum quantized LSF value (3.2.4)
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 * 3.135 in Q13
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 */
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#define LSFQ_MAX                   25681
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/**
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 * minimum LSF distance (3.2.4)
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 * 0.0391 in Q13
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 */
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#define LSFQ_DIFF_MIN              321
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/**
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 * minimum gain pitch value (3.8, Equation 47)
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 * 0.2 in (1.14)
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 */
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#define SHARP_MIN                  3277
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/**
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 * maximum gain pitch value (3.8, Equation 47)
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 * (EE) This does not comply with the specification.
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 * Specification says about 0.8, which should be
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 * 13107 in (1.14), but reference C code uses
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 * 13017 (equals to 0.7945) instead of it.
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 */
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#define SHARP_MAX                  13017
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typedef struct {
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    uint8_t ac_index_bits[2];   ///< adaptive codebook index for second subframe (size in bits)
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    uint8_t parity_bit;         ///< parity bit for pitch delay
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    uint8_t gc_1st_index_bits;  ///< gain codebook (first stage) index (size in bits)
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    uint8_t gc_2nd_index_bits;  ///< gain codebook (second stage) index (size in bits)
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    uint8_t fc_signs_bits;      ///< number of pulses in fixed-codebook vector
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    uint8_t fc_indexes_bits;    ///< size (in bits) of fixed-codebook index entry
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} G729FormatDescription;
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typedef struct {
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    int pitch_delay_int_prev;   ///< integer part of previous subframe's pitch delay (4.1.3)
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    /// (2.13) LSP quantizer outputs
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    int16_t  past_quantizer_output_buf[MA_NP + 1][10];
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    int16_t* past_quantizer_outputs[MA_NP + 1];
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    int16_t lsfq[10];           ///< (2.13) quantized LSF coefficients from previous frame
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    int16_t lsp_buf[2][10];     ///< (0.15) LSP coefficients (previous and current frames) (3.2.5)
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    int16_t *lsp[2];            ///< pointers to lsp_buf
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}  G729Context;
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static const G729FormatDescription format_g729_8k = {
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    .ac_index_bits     = {8,5},
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    .parity_bit        = 1,
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    .gc_1st_index_bits = GC_1ST_IDX_BITS_8K,
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    .gc_2nd_index_bits = GC_2ND_IDX_BITS_8K,
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    .fc_signs_bits     = 4,
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    .fc_indexes_bits   = 13,
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};
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static const G729FormatDescription format_g729d_6k4 = {
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    .ac_index_bits     = {8,4},
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    .parity_bit        = 0,
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    .gc_1st_index_bits = GC_1ST_IDX_BITS_6K4,
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    .gc_2nd_index_bits = GC_2ND_IDX_BITS_6K4,
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    .fc_signs_bits     = 2,
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    .fc_indexes_bits   = 9,
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};
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/**
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 * \brief pseudo random number generator
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 */
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static inline uint16_t g729_prng(uint16_t value)
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{
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    return 31821 * value + 13849;
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}
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/**
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 * Get parity bit of bit 2..7
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 */
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static inline int get_parity(uint8_t value)
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{
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   return (0x6996966996696996ULL >> (value >> 2)) & 1;
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}
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static void lsf_decode(int16_t* lsfq, int16_t* past_quantizer_outputs[MA_NP + 1],
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                       int16_t ma_predictor,
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                       int16_t vq_1st, int16_t vq_2nd_low, int16_t vq_2nd_high)
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{
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    int i,j;
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    static const uint8_t min_distance[2]={10, 5}; //(2.13)
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    int16_t* quantizer_output = past_quantizer_outputs[MA_NP];
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    for (i = 0; i < 5; i++) {
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        quantizer_output[i]     = cb_lsp_1st[vq_1st][i    ] + cb_lsp_2nd[vq_2nd_low ][i    ];
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        quantizer_output[i + 5] = cb_lsp_1st[vq_1st][i + 5] + cb_lsp_2nd[vq_2nd_high][i + 5];
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    }
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    for (j = 0; j < 2; j++) {
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        for (i = 1; i < 10; i++) {
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            int diff = (quantizer_output[i - 1] - quantizer_output[i] + min_distance[j]) >> 1;
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            if (diff > 0) {
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                quantizer_output[i - 1] -= diff;
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                quantizer_output[i    ] += diff;
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            }
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        }
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    }
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    for (i = 0; i < 10; i++) {
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        int sum = quantizer_output[i] * cb_ma_predictor_sum[ma_predictor][i];
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        for (j = 0; j < MA_NP; j++)
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            sum += past_quantizer_outputs[j][i] * cb_ma_predictor[ma_predictor][j][i];
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        lsfq[i] = sum >> 15;
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    }
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    /* Rotate past_quantizer_outputs. */
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    memmove(past_quantizer_outputs + 1, past_quantizer_outputs, MA_NP * sizeof(int16_t*));
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    past_quantizer_outputs[0] = quantizer_output;
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    ff_acelp_reorder_lsf(lsfq, LSFQ_DIFF_MIN, LSFQ_MIN, LSFQ_MAX, 10);
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}
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static av_cold int decoder_init(AVCodecContext * avctx)
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{
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    G729Context* ctx = avctx->priv_data;
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    int i,k;
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    if (avctx->channels != 1) {
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        av_log(avctx, AV_LOG_ERROR, "Only mono sound is supported (requested channels: %d).\n", avctx->channels);
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        return AVERROR(EINVAL);
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    }
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    /* Both 8kbit/s and 6.4kbit/s modes uses two subframes per frame. */
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    avctx->frame_size = SUBFRAME_SIZE << 1;
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    for (k = 0; k < MA_NP + 1; k++) {
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        ctx->past_quantizer_outputs[k] = ctx->past_quantizer_output_buf[k];
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        for (i = 1; i < 11; i++)
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            ctx->past_quantizer_outputs[k][i - 1] = (18717 * i) >> 3;
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    }
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    ctx->lsp[0] = ctx->lsp_buf[0];
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    ctx->lsp[1] = ctx->lsp_buf[1];
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    memcpy(ctx->lsp[0], lsp_init, 10 * sizeof(int16_t));
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    return 0;
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}
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static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
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                        AVPacket *avpkt)
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{
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    const uint8_t *buf = avpkt->data;
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    int buf_size       = avpkt->size;
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    int16_t *out_frame = data;
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    GetBitContext gb;
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    G729FormatDescription format;
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    int frame_erasure = 0;    ///< frame erasure detected during decoding
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    int bad_pitch = 0;        ///< parity check failed
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    int i;
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    G729Context *ctx = avctx->priv_data;
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    int16_t lp[2][11];           // (3.12)
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    uint8_t ma_predictor;     ///< switched MA predictor of LSP quantizer
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    uint8_t quantizer_1st;    ///< first stage vector of quantizer
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    uint8_t quantizer_2nd_lo; ///< second stage lower vector of quantizer (size in bits)
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    uint8_t quantizer_2nd_hi; ///< second stage higher vector of quantizer (size in bits)
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    int pitch_delay_int;         // pitch delay, integer part
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    int pitch_delay_3x;          // pitch delay, multiplied by 3
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    if (*data_size < SUBFRAME_SIZE << 2) {
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        av_log(avctx, AV_LOG_ERROR, "Error processing packet: output buffer too small\n");
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        return AVERROR(EIO);
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    }
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    if (buf_size == 10) {
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        format = format_g729_8k;
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        av_log(avctx, AV_LOG_DEBUG, "Packet type: %s\n", "G.729 @ 8kbit/s");
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    } else if (buf_size == 8) {
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        format = format_g729d_6k4;
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        av_log(avctx, AV_LOG_DEBUG, "Packet type: %s\n", "G.729D @ 6.4kbit/s");
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    } else {
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        av_log(avctx, AV_LOG_ERROR, "Packet size %d is unknown.\n", buf_size);
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        return AVERROR_INVALIDDATA;
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    }
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    for (i=0; i < buf_size; i++)
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        frame_erasure |= buf[i];
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    frame_erasure = !frame_erasure;
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    init_get_bits(&gb, buf, buf_size);
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    ma_predictor     = get_bits(&gb, 1);
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    quantizer_1st    = get_bits(&gb, VQ_1ST_BITS);
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    quantizer_2nd_lo = get_bits(&gb, VQ_2ND_BITS);
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    quantizer_2nd_hi = get_bits(&gb, VQ_2ND_BITS);
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    lsf_decode(ctx->lsfq, ctx->past_quantizer_outputs,
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               ma_predictor,
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               quantizer_1st, quantizer_2nd_lo, quantizer_2nd_hi);
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    ff_acelp_lsf2lsp(ctx->lsp[1], ctx->lsfq, 10);
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    ff_acelp_lp_decode(&lp[0][0], &lp[1][0], ctx->lsp[1], ctx->lsp[0], 10);
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    FFSWAP(int16_t*, ctx->lsp[1], ctx->lsp[0]);
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    for (i = 0; i < 2; i++) {
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        uint8_t ac_index;      ///< adaptive codebook index
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        uint8_t pulses_signs;  ///< fixed-codebook vector pulse signs
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        int fc_indexes;        ///< fixed-codebook indexes
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        uint8_t gc_1st_index;  ///< gain codebook (first stage) index
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        uint8_t gc_2nd_index;  ///< gain codebook (second stage) index
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        ac_index      = get_bits(&gb, format.ac_index_bits[i]);
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        if(!i && format.parity_bit)
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            bad_pitch = get_parity(ac_index) == get_bits1(&gb);
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        fc_indexes    = get_bits(&gb, format.fc_indexes_bits);
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        pulses_signs  = get_bits(&gb, format.fc_signs_bits);
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        gc_1st_index  = get_bits(&gb, format.gc_1st_index_bits);
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        gc_2nd_index  = get_bits(&gb, format.gc_2nd_index_bits);
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        if(!i) {
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            if (bad_pitch)
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                pitch_delay_3x   = 3 * ctx->pitch_delay_int_prev;
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            else
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                pitch_delay_3x = ff_acelp_decode_8bit_to_1st_delay3(ac_index);
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        } else {
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            int pitch_delay_min = av_clip(ctx->pitch_delay_int_prev - 5,
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                                          PITCH_DELAY_MIN, PITCH_DELAY_MAX - 9);
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            if(packet_type == FORMAT_G729D_6K4)
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                pitch_delay_3x = ff_acelp_decode_4bit_to_2nd_delay3(ac_index, pitch_delay_min);
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            else
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                pitch_delay_3x = ff_acelp_decode_5_6_bit_to_2nd_delay3(ac_index, pitch_delay_min);
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        }
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        /* Round pitch delay to nearest (used everywhere except ff_acelp_interpolate). */
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        pitch_delay_int  = (pitch_delay_3x + 1) / 3;
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        ff_acelp_weighted_vector_sum(fc + pitch_delay_int,
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                                     fc + pitch_delay_int,
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                                     fc, 1 << 14,
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                                     av_clip(ctx->gain_pitch, SHARP_MIN, SHARP_MAX),
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                                     0, 14,
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                                     SUBFRAME_SIZE - pitch_delay_int);
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        if (frame_erasure) {
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            ctx->gain_pitch = (29491 * ctx->gain_pitch) >> 15; // 0.90 (0.15)
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            ctx->gain_code  = ( 2007 * ctx->gain_code ) >> 11; // 0.98 (0.11)
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            gain_corr_factor = 0;
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        } else {
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            ctx->gain_pitch  = cb_gain_1st_8k[gc_1st_index][0] +
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                               cb_gain_2nd_8k[gc_2nd_index][0];
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            gain_corr_factor = cb_gain_1st_8k[gc_1st_index][1] +
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                               cb_gain_2nd_8k[gc_2nd_index][1];
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        ff_acelp_weighted_vector_sum(ctx->exc + i * SUBFRAME_SIZE,
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                                     ctx->exc + i * SUBFRAME_SIZE, fc,
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                                     (!voicing && frame_erasure) ? 0 : ctx->gain_pitch,
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                                     ( voicing && frame_erasure) ? 0 : ctx->gain_code,
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                                     1 << 13, 14, SUBFRAME_SIZE);
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            ctx->pitch_delay_int_prev = pitch_delay_int;
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    }
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    *data_size = SUBFRAME_SIZE << 2;
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    return buf_size;
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}
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AVCodec ff_g729_decoder =
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{
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    "g729",
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    AVMEDIA_TYPE_AUDIO,
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    CODEC_ID_G729,
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    sizeof(G729Context),
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    decoder_init,
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    NULL,
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    NULL,
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    decode_frame,
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    .long_name = NULL_IF_CONFIG_SMALL("G.729"),
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};